Oxidative stress and mitochondrial dysfunction are centrally involved in the etiology of several diseases and in the normal process of aging. The protein DJ-1 is an oxidative stress response protein whose absence or dysregulation has been implicated in parkinsonism, cancer, and stroke. DJ-1 can robustly protect cells against multiple forms of oxidative stress and thereby confer protection against degeneration that can lead to disease. The molecular mechanism(s) of DJ-1's action, however, remains unclear. DJ-1 contains a functionally essential cysteine residue whose oxidation is hypothesized to regulate its cytoprotective function. We will investigate the mechanism by which DJ-1 senses and responds to oxidative stress by accomplishing three specific aims. The first aim will investigate the role of DJ-1 cysteine oxidation in the protection against oxidative stress in the Drosophila animal model system. We will combine X-ray crystallography, biochemistry, and Drosophila genetics to establish a powerful animal model for the redox regulation of DJ-1 function. The second aim will determine the structure-function relationships for an established mRNA binding activity of DJ-1. The results will be used to test the hypothesis that conserved structural features near the oxidized cysteine integrate the RNA binding and redox sensing functions of DJ-1. The third aim will use a prokaryotic model system to investigate the evolutionarily conserved mechanism of DJ-1 protective function. The results will be used to test existing hypotheses about the conservation of regulatory cysteine oxidation in DJ-1 function as well as discover new functions for DJ-1. In total, the proposed research will provide a comprehensive molecular basis for understanding the oxidative regulation and pathogenic disruption of DJ-1 function. Ultimately, the results of this research will be used to design a new generation of therapeutics that enhance the protective function of DJ-1 in vulnerable cell types. PUBLIC HEALTH RELEVANCE: Oxidative stress and mitochondrial dysfunction are centrally involved in several human diseases. Major recent advances have identified DJ-1 as a protein that confers robust protection against oxidative stress. The precise biochemical function of DJ-1, however, remains uncertain. The long-term goal of this proposal is to determine the biochemical functions of DJ-1 that confer protection against oxidative stress and with the goal of developing therapies that improve the protective function of DJ-1.